1. Field of the Invention
The present invention relates, in general, to a method of preparing polycarboxy alkyl and aryl phosphonates and polymeric compositions thereof, and further concerns flame retardant systems incorporating said phosphorus structures.
2. The Prior Art
Polycarboxy alkylphosphonate monomers are known and are described by A. N. Pudovik et al., Zhurnal Obschei Khimii, Vol. 30, No. 8, pp. 2624-2630, August, 1960. Pudovik et al. disclose, among others, compositions having the structural formula: ##STR3## where R' is hydrogen, CH.sub.3, C.sub.2 H.sub.5, or C.sub.3 H.sub.7.
The Pudovik et al. compounds are prepared according to the following general reaction scheme: ##STR4## where X is I, Br or Cl and R" and R''' are the same or different and have the same definition as R'.
Rates of reaction in the Pudovik et al. method are slow. Moreover, Pudovik et al, employed equimolar quantities of reactants; which resulted in mixtures of mono- and dicarboxy phosphonates.